Fractionation of crude petroleum oil



Jail

United States "Patent FRACTIONATION 0F CRUDE PETROLEUM OIL :Robert G.Capell, Clarence Karr, Jr., and William D. Weatherford, Jr., Pittsburgh,Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa.,a corporation of Delaware No Drawing. Application June 24, 1952, SerialNo. 295,354

3 Claims. (Cl. 196-147) The present invention relates to thefractionation of crude petroleum and more particularly to a method ofseparating the constituents of crude petroleum on the basis of moleculartypes by chromatographic fractionation.

The frictionation of crude oil by distillation has a number ofdisadvantages. For example, fractional distillation separates the crudeconstituents according to boiling points or molecular weights ratherthan according to molecular types so that it is impossible bydistillation alone to obtain from most crudes, motor fuel fractions orcracking stock fractions free from undesirable substances such as sulfurcompounds or metal compounds boiling in the same temperature ranges asthe desired fractions. Consequently in conventional refinery operations,it is necessary, following the recovery of desired fractions bydistillation, to subject such fractions to further refining for theremoval of undesirable materials which distill with the desiredmaterials. Molecular types such as sulfur compounds, diolefins andactive monoolefins formed on distillation, aromatics, metal compounds,and asphaltic and resinous materials are distributed among several ofthe distillation fractions. Relatively expensive and complicatedprocedures must be applied to each of the fractions to separate thedesired types from the undesirable ones. Thus it is conventional tosubject gasoline fractions to copper sweetening to convert mercaptans toless obnoxious sulfur compounds or to processes for the removal ofsulfur. In the case of kerosenes it is the usual practice to removearomatics by sulfur doxide extraction or by. heavy acid treatment. Whengas oils charged to catalytic cracking units contain metals, thesemetals deposit on the cracking catalyst and can have an adverse effect.posits, unlike coke deposits, cannot be removed by oxidativeregeneration, and it is therefore desirable to prepare metal-freecracking stocks. Lubricating oil stocks are subjected to severalrefining processes to produce salable lubricants.

Another characteristic of distillation fractionation which is frequentlyundesirable is the resulting thermal decomposition of at least some ofthe crude oil constituents. In fractionating a crude oil into severalfractions by distillation fractionation, it is impossible to recovermany of the valuable chemicals of the crude petroleum in their naturalstate because they are thermally decomposed under the conditionsnecessary for this type .of distillation.

Our present process has none of the indicated disadvantages offractional distillation. By our process it is possible to separate theconstituents of a crude oil ac- ..cording to molecular types and obtainfractions which .consist essentially of compounds that occur naturallyin .crude oil, that is, compounds which have undergone no thermalconversion during the fractionation process, and it is possible toseparate compounds which are desirable a particular refinery productfrom those which are un- Such metal de- I 2,776,250 i atented Jan. 1,1957 desirable. Thus, for example, by our process it is possible toobtain from a total crude oil, fractions such as: essentially pureparaffins; essentially pure mononuclear aromatics; essentiallycolorless, sulfur-free, oxygen-free and metal-free hydrocarbons; sulfurcompound concentrates which are essentially asphalt-free and metal-free;sulfur compound concentrates which are essentially color less andmetal-free; and mixtures which are rich in sulfur, asphalt and metals.Certain of these fractions are ideal sources of motor fuels, crackingstocks, lubricating oil stocks, and other valuable products. Other ofthe fractions have importance from the petro-chemical point of viewsince they contain high concentrations of valuable naturally occurringpetroleum compounds.

We have discovered in accordance with the invention that crude oils canbe separated into a plurality of valuable fractions without substantialdestruction of the compounds existing in the crude oil by subjecting thecrude oil to elution chromatography as described more fully hereinafter.An important feature of the invention is based upon the discovery thatan alumina adsorbent material, especially bauxite, is markedly superiorto other adsorbents for the fractionation of crude petroleum oils.

Our process in genera-l comprises passing into contact with a bed ofadsorbent material selected from the group consisting of activatedalumina and activated bauxite a liquid comprising at least about 25percent by volume crude oil in an amount which penetrates no more thanabout percent of the adsorbent bed. The bed is then contacted with aseries of eluant liquids of successively increasing eluting powers. Eacheluate is collected as it emerges from the bed either as one fraction orin a number of successively collected portions to obtain fractions ofunconverted natural petroleum compounds.

An important element in our process is the maximum quantity of oil to befractionated which can be charged to the adsorbent bed. In other words,the ratio of charge to adsorbent is important. This ratio is importantbecause if an excessive volume of charge is introduced to the column,the fractionation will begin as a percolation process and it will beimpossible to obtain sharp unmixed fractions which are obtainable by ourprocess. To avoid mere percolation of any of the oil, it is necessarythat the amount of charge be substantially less than the amountnecessary to penetrate the entire bed. Therefore, when the charging ofthe crude oil is terminated and the introduction of the first eluant isbegun, there must still be a portion of the bed which is unpenetrated bythe charge oil.

In our process the liquid mixture comprising crude oil is introduced tothe adsorbent bed at either extremity thereof in an amount which isinsufiicient to penetrate the entire bed. The oil must penetrate no morethan about 90 percent of the bed. There is no lower limit for the amountof oil that can be charged as far as obtaining sharp fractions inconcerned. However, to use the capacity of the column most efficientlythe amount should not be unreasonably small. In general, it can be saidthat the amount of oil charged should be that which will penetrate fromabout 5 to 90 percent of the adsorbent bed. It will be understood,however, that the extent of penetration within this range adapted toaccomplish desirable fractionation will vary depending upon such factorsas the specific composition of the crude oil, the particular adsorbentused, and the equipment employed. Accordingly, in many cases the processshould be carried out in such manner that the charge oil penetratessubstantially less than 90 percent of the adsorbent bed.

The simplicity and efficiency of our process are at their greatest whenundiluted, untreated total crude oil is the charge mixture. However, inaddition to total crude.

the charge stock for our process can also be topped or reduced crudeoil, deasphalted crude, or mixtures of such stocks with total crude. Thepreparation of these stocks does not involve the use of distillationssevere enough to cause any important decomposition of their valuableconstituents, and it will be understood that when unconverted naturallyoccurring petroleum compounds are referred to herein and in the claims,the compounds present in topped, reduced or deasphalted crude oils areincluded. While it is generally unnecessary to dilute such stocks forfractionation by our process, it may be desirable to moderately dilutevery viscous liquids so that they will pass readily through theadsorptive bed. Heavy stocks which might require dilution are totalcrudes of very high viscosity such as Mississippi crude, or topped orreduced crudes. The diluent can in general be any solvent for the crudeoil which is not so strongly adsorbed in the adsorbent bed as toinactivate the bed for fractionating the crude oil. Suitable diluentsinclude liquids such as hydrocarbons of the naphtha, kerosene, gas oil,or fuel oil ranges. Among the possible nonhydrocarbon diluents might bementioned halogenated hydrocarbons or nitrobenzene. It is also possibleto dilute ,a high viscosity stock with a lighter crude oil if desired.Still another possibility is the use of a low viscosity product of ourprocess as the diluent.

Excessive dilution of the crude oil must be avoided because .the.adsorbent column capacity is inefficiently employed when a large amountof diluent liquid is added to the crude oil to be separated. It is notpossible to specify proper degrees of dilution which will be suitablefor all the heavy stocks because of the wide variations in viscosity ofsuch stocks. However, the crude should not be diluted to a concentrationbelow about 25 percent by volume. In more dilute concentrations thanthis, the maximum efficiencyof the column for fractionating crude oilsis not obtained.

An important element of our process is the particular adsorbentmaterials employed because the class of adsorbents which we use isessential to the production of substantially sulfur-free, metal-free,oxygen-free and colorless fractions which are characteristic of ourprocess. The adsorbent in our process is an alumina or bauxite. Theadsorbent aluminas which can be used are those available commercially asalumina and which analyze 99.0 percent A1203 on a volatile-free basisand materials which consist predominantly of alumina such as those whichconsist of alumina and a minor amount of other compounds, such assilica. Bauxites, which can be obtained commercially in adsorbent formunder such trade names as Porocel and Florite, are well-known products,and are activated by heat treating bauxite ores.

Theadsorbent is preferably employed in granulated form. We have foundthat excellent yields are obtained when the particle size is betweenabout and 200 mesh. Very small particles are undesirable because thechilicultyof removing all of the charge liquid from the adsorbent bedincreases as the proportion of fines increases. The adsorbent materialis preferably disposed in an elongated vertical column. It is activatedbefore use as by heating to an elevated temperature for several hours.The temperature of activation is not critical, but we have foundthattemperatures between about 250 and 1400" -F., and preferably betweenabout 400 and 800 F, give good results.

Immediately following introduction of the crude oil charge, thedevelopment of the chromatogram is begun by introducing the first eluantliquid to the bed. This first eluant is chosen according to its elutivepower to produce the typeof first fraction desired. To assist in theselection of the proper sequence of eluant liquids, they can beconveniently grouped according to their relative elutive'powers. Thefollowing table lists a suitable grouping of several typesofeluantliquids:

TABLE I Weak Eluants Moderate Eluants Strong Eluants n-pentane. hot weakeluant. hot moderate eluants. mixed pentanes. weak eluant modmoderateeluant petroleum ether. crate eluant. strong eluant. parafiinic mixture.carbon tetrachloride. 25% ethanol in benoyclohcxane. zene.

maphthenic mixture. ethanol.

benzene. methanol.

aromatic mixture. solvent polar compound. polar solvent.

If it is desired to obtain a first fraction which is substantiallycolorless, sulfur-free, metal-free, and oxygenfree, and adsorbent columnshould be first eluted with a weak eluant, such as one of those ofthefirst column of Table I whch will not excessively elute undesiredsubstances from the column. This is our preferred procedure. However, ifa large first fraction is desired, e. g., a deasphalted crude, and thereis no objection to its containing substances such as sulfur compounds,:1 moderately strong first eluant can be chosen, such as an eluant fromthe second column of Table I. The volume of the eluant employed in eachstage depends upon the desired separation but is preferably at leastabout one to five times the volume of the charge liquid. Much largervolumes of eluant can be employed, of course, but without improving thefractionation to any important degree. Following the elution with afirst stage eluant, the bed is contacted with a second stage eluant ofstronger elution power to recover a second fraction and thereafter, ifdesired with a third eluant of still stronger eluting power to recover athird fraction. More eluants can be used if more fractions are desired.The final eluant, if desired, can be a strongly adsorbed liquid whichacts as a displacer liquid to displace all remaining adsorbed substancesfrom the adsorbent bed.

It will be noted from Table I above that a moderate eluant mixed with aweak eluant yields a moderate eluant, and a strong eluant mixed with amoderate eluant yields a strong eluant. Thus, the elutive power of aweak or moderate eluant is greatly increased by the addition of evenvery minor amounts of a stronger eluant. Accordingly, for the efiicientrecovery of fractions of weak- 1y adsorbed substances such a paraflins,naphthenes, and mononuclear aromatics without the inclusion of morestrongly adsorbed substances such as sulfur compounds it is importantthat the eluant employed be a weak eluant which is uncontaminated by anystronger eluant which would cause the elution of undesired substanceswith the weak eluant fraction. The mixture of two or more eluants havingabout the same order of elutive powers is not usually objectionable butthe inclusion of even a very small quantity, e. g. 0.5 percent, of astrong eluant can form. a.mixture having a much stronger elutive powerthan the major constituents of weak elutive power. This principlegoverns the purity of eluants that can be used for elutingthe firstfractions from the adsorbent bed. Thus, to obtain the total weak eluantfraction as a colorless, sulfur-free, and metal-free fraction, it isessential thatthe first eluant be a weak eluant such as a parafiinliquid which contains no appreciable quantity of stronger eluants-suchas aromatics or polar compounds. The weak eluant can in most cases,however, consist of mixtures of paraffins. It is clear from these factsthat it is important in .a cyclic process in accordance with ourinvention to recover the eluants from the products substantiallyuncontaminated by liquids with a higher order of eluting power beforeagain using them as eluants in another cycle. The described effect ofthe addition of a strong eluant to a weak eluant has the advantage ofmaking it possible to employ as the moderate or strong eluants, mixtures.which are predominantly relatively inexpensive paralfinsand-.whichcontain only minor amounts, sufficient to give the desiredeluting power, of more expensive stronger eluants such as aromatics orpolar solvents.

The importance in our process of using first stage eluants which areunmixed with stronger eluants is related to the previously mentionedimportant element of the process, the maximum charge to adsorbent ratio.Thus if the volume of charge introduced to the adsorbent bed beforeelution is begun exceeds the capacity of the bed, the charge in the bellwill in effect be eluted by the portion of charge which exceeds thecapacity of the bed. Since the charge comprises a crude oil andtherefore con tains substances which are moderate or strong eluants, thebed will be first eluted by a moderate or strong eluant. It is, ofcourse, essential in our process that the bed be elutive by a series ofeluants of successively increasing elutive powers and therefore theelution of the bed by a portion of the charge itself before the firststage elution with a weak eluant would make it impossible to obtain theproper fractionation of the charge. In addition, poor recovery of weaklyadsorbed substances would result from elution with a portion of thecharge itself, since these substances would be distributed throughoutthe bed owing to their presence in the entering charge.

As mentioned above, the alumina or bauxite adsorbent employed in ourprocess can be an activated alumina adsorbent which is substantiallypure alumina or one which consists predominantly of alumina or it can bethe activated natural alumina, bauxite. We have discovered, however,that bauxite is especially valuable in the present process. We havefound that when using bauxite, the separation between sulfur compoundsand hydrocarbons free from sulfur is especially sharp. Thus, whenactivated bauxite is employed as the adsorbent material, we have foundthat a weak paraffinic eluant will not desorb substantial amounts ofsulfur from the adsorbent. It is therefore possible in accordance withthe invention to recover the entire eluate obtained with the weak eluantas a colorless, substantially sulfur-free and metal-free fraction whichcontains substantially all of the paraffinic, naphthenic and mononucleararoma-tic compounds of the crude oil.

As described, it is possible in our process to separate a crude oil intoa small number of fractions by recovering the entire liquid eluted by aneluant as a single fraction. However, it is usually preferred to takeadvantage of the differences in adsorbabili-ty of the crude oilconstituents and collect the liquid issuing from the adsorbent bed ineach elution stage in a number of portions. Thus, because of theirdifferences in adsorbability certain types of compounds will emerge fromthe column first, and other types will follow successively dependingupon their strengths of adsorbability. If proper cuts are made of theemerging liquid, it is possible to collect fractions of substantiallysingle types of petroleum compounds. This technique can be applied toany of the elution stages of our process and has particular applicationin fractionating crude petroleum for the recovery of valuablepetrochemicals.

We have found that a first-stage Weak paraffinic eluant will elute somesulfur compounds from alumina adsorbent bed. However, we have discoveredthat sulfur is not eluted by the paraffinic liquid uniformly throughoutthe Weak eluant stage, but rather that sulfur compounds begin to appearin the eluate only after a considerable quantity of eluate has emergedfrom the bed. We have also discovered that the occurrence of sulfur inthe eluate corresponds closely With the occurrence of compounds whichfluoresce in ultraviolet light. Consequently, We are able to collect asulfur-free fraction by observing the fluores cence under ultravioletlight of the emerging eluate and separating the collected material whenfluoroescence first appears.

cessively increasing eluting powers, for example, by ani eluant ffom thesecond column of Table I, and then by an eluant from the third column ofTable I. In each of these elutions the volume of the eluant ispreferably about one to five times the volume of the charge oil,although larger volumes of eluant can be used.

The fractionation process of our invention can be readily adapted tocontinuous or cyclic operation. In such a case, following the finalelution with a strong eluant the adsorbent bed is purge-d of the strongeluant to prepare :for the next cycle. It is possible to remove centainfinal stage eluants from the bed simply by wash-- ing the bed with thefirst stage eluant for the next cycle.

However, other final stage eluants must be removed in. stages. Thus, forexample, in a process employing n-pentane, benzene, and ethanol as thefirst, second, and:

third stage eluants respectively, it is impossible or impracticable toremove completely the ethanol remaining: in the bed after the finalelution by merely purging the: bed with cold pentane. A suitableprocedure is to waslr the bed with benzene after the ethanol elution toremove the ethanol and then with pentane to remove the benzene beforecommencing the next fractionation cycle.

At the start of our fractionation process, the adsorbent bed can beeither dry or wet but it is preferred to prewet the bed with the firststage eluant or with a Weaker eluant before introducing the crude oil tobe fractionated. Prewetting is desirable for several reasons. In acyclic process it assists in removing from the bed the last traces bedis eluted with a series of additional eluants of sucof the final stageeluant of the previous fractionation cycle. Prewett-ing also causes thecrude oil charge to penetrate more readily the adsorbent bed and reduceschanneling in the bed. Still further, prewetting reduces or eliminatesthe heat of wetting when the crude oil is introduced to the bed. Theheat evolved on contacting a crude oil with a dry adsorbent bed canraise the tempenature of particles of oil in contact with the adsorbentsufficiently to cause thermal decomposition of some of the desiredconstituents of the crude oil. Since one of the important advantages ofour process is the fractionation of crude oil without thermaldecomposition of its valuable components, it would thus be desirable toavoid introducing the charge to a dry bed if the heat of wetting wouldbe such as to cause substantial thermal decomposition.

In the continuous operation of our process, a plurality of adsorbentbeds can be employed so that the charge oil can be introduced to one oranother of the beds at all times while the other beds are undergoingelution or purging. Small quantities of materials may be unremovablefrom the bed by the usual eluting solvents and in such cases the bed canat intervals be subjected to regeneration such as by burning to removeaccumulated carbonaceous deposits.

We have fractionated several different crude oils by our process andalso by unsatisfactory processes using nonalumina adsorbents, i. e.adsorbents other than bauxite or alumina.

Tables 1H, III, IV, and V below record the inspection data for the WestTexas, McElroy West Texas, Kuwait, and Baxtervill-e, Mississippi, crudeoils respectively which we have fractionated.

TABLE 11 West Texas crude Gravity, API at 60 F 35.2 Viscosity, F,centistokes 4.79 Sulfur, wt. percent 1.40 Chlorides, as NaCl, lbs./ 1000bbl 21.8 ASTM distillation:

I.B.P 118 F. 10% 248 F. 20% 316 F. 30% 375 F., 45.3% over at 500 F.

40% 466 F., 58.1% over at 590 F.

BLE ontinu ASTM distillation:

TABLE 111 McElroy West Texas crude We have fractionated the West Texascrude oil of Table F FY DAPIO at II above in accordance with our processusing granular Vlscosltyq activated alumina as the adsorbent and usingfour succemlstokes cessive eluant liquids: n-pentane, carbontetrachloride, benzene, and a mixture of 25 percent by volume of ethanoll l" Percent: in benzene. The procedure followed is described in EX- gegengf amplelbelow. chlorides, as NaCl, lbs/1000 bbl Nil Examplel ASTMdistillation: The total undiluted West Texas crude oil was intro- P 0 Rduced at the top of a column of 80-200 mesh activated 2 R alumina in theamount of about 0.15 volume of crude 5% 0 oil per volume of adsorbent.The charge penetrated 10% F about 35 percent of the bed. Immediatelyafter lntro- 20% 0. duction of the entire crude oil charge, the columnWas 30% F eluted by introducing at the top of the column about 9 40% 0parts by volume of n-pentane per part of charge 011. 453% 0 F,(obviouscmcking) The entire amount of liquid eluted In this stage wasrecovered as a single fraction. Following elution with TABLE n-pentanethe column was eluted successively with about Kuwait crude equal amountsof carbon tetrachloride, benzene, and a Gravity at F 5 solution of 25percent ethanol in benzene. In each stage Viscosity the entire eluatesolution was collected as a single frac- Centistokcs 9:36 tion and theeluant was evaporated from the crude oil U S traction by heating thesolution to 50-60 C. while sweepsulfur Wt Percent 259 mg its surfacewith a stream of nitrogen. In each stage chlorides, as Nacl, 1bs/1O00|bb1 of the chromatographic fractionation, the liquids were passedthrough the adsorbent column by gravity flow and AsTMdlstl'nat'lom O nochanneling difiiculties were encountered. The frac- P 106 tionation wascarried out at room temperature or about 10% 256 77 1; 392 The resultsof the Example I fractionation of the West Texas crude oil are recordedin Table VI below in terms 590 40 of the yields and characteristics ofeach fraction obtained. TABLE V It will be noted from Table VI thatmaterial losses were substantial. These losses resulted from theevapora- Baxtewllle Cmde tion of the light ends of the crude oil whileseparating Gravity, API at F 15.8 the eluant liquid from the crude oilfraction. The ad- Viscosity, F.: 45 sorbent bed after the final elutionwith the ethanol-ben- Centistokes 822.7 zene mixture had the same whiteappearance that it had S, U. S -e 3801.0 at the start of the process,thus indicating that the crude Sulfur, wt. percent 2.83 oil charge hadbeen substantially entirely removed from Chlorides, as NraCl, lbs./ 1000bbl '10 the bed.

TABLEVI Eluant. n-pentant CClt benzene 26% ethanol in benzene MassRecovery:

Wt. Percent 01 Charge 48. 5 15.1 5. 3 6. 6

Total Wt. Percent 75. 5

Sulfur Content, Wt. Percent 0. '19 4. s4 5. 29 3. 72

Sulfur Recovery:

Wt. Percent of Sulfur in Charge 6.6 47. 4 20. 2 17. 7

Total Wt. Percent 91. 9

Appearance colorlessoiL. darl; orange. dark brown black tar. Odorpleasant"... tuiz fleasantn asg halticuu asplfialtitlrand p cue to.ititi iiiiiifiift t t fiiifi i fiiiiiii31111133333: 53% blue T CarbonContent, Wt. Percent... Hydrogen Content, Wt. Percent Oxygen Content,Wt. Percent Corrected Mass Recovery: I Wt. Percent oi charge. 73

1 All material losses were light ends.

From Table VI above it can be seen that our process produced a colorlessfraction amounting to 73 percent 10 teristics of each fraction Obtainedare given in Table VIIbelow.

TABLE VII Re- Corrected S S Recovery, Re- Content, covery, Fraction Wt.covery 1 Wt. Wt. Fluorescence Crude 011 No. Eluant Percent Wt. PercentPercent Appearance Odor Under U. V.

of Percent of of S in Light Charge of Fraction Charge Charge 1 n-petane49. 7 64. 2 0. 08 1. 7 Grgofless Pleasant. None.

1 2 benzene 25. 4 25. 4 6. 32 67. 4 Dark orange Unpleasant Blue. McElroyCrude, 2.38% S 011.

, 3 25 vol. percent 10. 4 10. 4 5. 31 23. 2 Brown- Asphaltlc- Brown.

ethanol in black benzene. semi-solid.

Total Recovery 85. 5 100. 92. 3

1 n-pentane 40. 6 56. 4 0. 0.8 Colorless Pleasant. None.

01 2 benzene 30. 3 30.3 5.15 60.2 Brown oil Unpleasant Green-blue.Kuwalt Crude, 259% S 3 vol. percent 13. a 13v 3 6.05 31.1 Brown-Asphaltic... Brown.

ethanol in black benzene. semi-solid.

Total Recovery 84. 2 100. 0 92. 1

1 All material losses were light ends.

by weight of the crude oil charge based on corrected mass recoverycalculations. This large fraction obtained from the high sulfur WestTexas crude oil contained only 0.19 percent by weight sulfur and wasoxygen free. The

pleasant odor of this eluate substantiates its low sulfur analysis. Thecarbon tetrachloride eluate contained 4.34

percent sulfur and thus had a high concentration of sulfur compounds. Onan estimated average molecular weight of 446 for this carbontetrachloride eluate, the

calculated sulfur compound content is about 60 percent, assuming onesulfur atom in each sulfur compound molecule. Therefore, this eluate isa valuable source of sulfur-containing chemicals. The benzene eluatecontained 5.29 percent sulfur and contained an even higher proportion ofsulfur compounds than the carbon tetrachloride eluate. four fractionsobtained increase successively in average molecular weight and that theratio of carbon to hydrogen increases correspondingly, the latter ratioindicating the increased aromaticity and decreased paraflinicity of eachsuccessive eluate.

We have fractionated the McElroy West Texas crude of Table III above andthe Kuwait crude of Table IV by our process using our preferredadsorbent, bauxite. The procedure employed is described in Example IIbelow.

Example II The adsorbent in each fractionation was the 60-100 meshactivated bauxite known commercially as Regular Iron Porocel. In eachfractionation the crude oil was introduced to the adsorbent column inthe manner described in Example I, in a charge to adsorbent ratio ofabout 0.14:1. This amount of oil penetrated about percent of the bed. Ineach run after introduction of the undiluted total crude oil charge, thecolumn was eluted with three successive eluants, n-pentane, benzene, anda mixture of 25 volume percent ethanol in benzene. In each elution stagethe eluant to charge volume ratio was 10:1 or greater. The recoveredeluate solutions were placed in shallow vessels under a ventilating hoodto separate the eluants from the crude oil fractions by evaporation. Theresults of fractionating the McElroy and Kuwait crude oils in terms ofquantities and charac- It should also be noted in Table VI that the l InTable VII above it can be seen that our fractionation process gaveexcellent results in fractionating the Mc- Elroy and Kuwait crude oils,both of which have high sulfur contents, but which differ in otherrespects. The table shows that there was obtained from the McElroy crudea n-pentane eluate comprising 49.7 percent of the original crude. Whencorrections are made for the losses in evaporating to separate theeluant from recovered fractions the yield is about 64 percent. Thislarge fraction was colorless and substantially sulfur free.

Table VII also shows the production of a large colorless and sulfur-freefraction from the Kuwait crude oil. The n-pentane eluate of the Kuwaitcrude amounted to 40.6 percent of the original crude or about 56percent, with corrections made for losses of light ends in evaporatingto remove the eluant. It should be observed that in fractionating theMcElroy and Kuwait crudes with bauxite as the adsorbent, the entirepentane eluate in each fractionation was substantially sulfur free sothat a collection of the pentane eluate in a plurality of portions tosegregate sulfur compounds was unnecessary.

We have also fractionated in accordance with our process the three crudeoils of Tables III, IV, and V, using activated alumina as the adsorbentas described in Example III below.

Example III The McElroy, Kuwait, and Baxterville crude oils of TablesIII, IV, and V, respectively, were fractionated as described in ExampleI, using -200 mesh activated alumina as the adsorbent. In eachfractionation the adsorbent column was eluated in three stages, theeluants in the order of their use being, n-pentane, benzene, and amixture of 25 percent ethanol in benzene. In each elution stage theeluant to charge ratio was about 10: 1. The McElroy and Kuwait crudeswere charged undiluted to the adsorbent column but the high viscosityBaxterville crude oil was diluted wtih an equal volume of n-pentane tocause it to pass more easily into the adsorbent bed. The results ofthese fractionations in terms of the quantities and characteristics ofthe fractions obtained are recorded in Table VIII below.

TABLE VIII Recovery, Corrected Sulfur Sulfur Frac- Wt. Per- Recovery,Content, Recovery, Fluorescence Crude 011 tion cent of Wt. Per- Wt. Pcr-Wt. Per- Appearance Odor under U. V.

No. Charge cent of cent of cent of S Light Charge Fraction in Charge 151.0 67.7 0.18 3.9 golorlessflOlL. geasantnguh lgzitle blue. 2 23.3 23.36. 53 63.9 rown np easan ue-green. McEmy Crude 238% 3 9.0 9.0 6.70 25.3Brown-black Asphaltlc Brown.

semi-solid.

Total Recovery 83.3 100.0 93.1

1 44.7 58.3 0.20 3.5 golorless 01i{l 6l 1 gleasantninn gialggpe. 2 29.829.8 6.00 69.1 rownac np easan g rown. Kuwa omdermm 3 1119 11.9 s43 25.0Brown-black Aspha1tic Brown.

semi-solid.

Total Recovery 86.4 100. 0 97. 6

1 41.5 0.10 1.5 Colorless O1l Pleasant Pale blue. 2 45.2 4.74 76.7Highly: vllscous Mild asphaltic Brown. Bat 1110 (1,2. S. ac oi.

X erv e m e 83% 3 14.0 4.68 23.3 Black tar Mild burnt Do.

odor.

Total Recovery 100.7 101. 5

I All material losses were light ends.

The results recorded in Table VIII show that our process employingactivated alumina as the adsorbent is applicable to crude oils of widelyvarying characteristics. Each of the crude oils fractionated had a highsulfur content but our process produced from each crude a large fractionof very low sulfur content colorless oil and the sulfur was concentratedin the strongly adsorbed fractions of the crude. The results areparticularly surprising with the Baxtcrville crude. From this veryheavy, highly carbonaceous crude oil it was possible to obtain afraction comprising 41.5 percent of the crude oil which was colorlessand contained only 0.10 percent sulfur.

We have also fractionated the West Texas crude of Table II using fivedifferent adsorbent materials as described in Example IV below.

Exampie IV The West Texas crude of Table II was fractionated using fivedifferent adsorbent materials. Two of the adsorbents used wereadsorbents of our process, namely activated alumina and activatedbauxite. The three other adsorbents were non-alumina adsorbents, namely,30170 mesh Florisil (a synthetic magnesium silicate), 30-170 meshfullers earth, and 28-200 mesh silica gel. Three successive eluants wereused in each fractionation: n-pentane benzene, and 25 percent ethanol inbenzene, The charge to adsorbent ratio in each farctionation was about0.15 to 1 which in each case was sufficient to cause penetration of fromabout 30 to 40 percent of the bed by the charge oil. In each eluti'onstage the eluant to charge ratio was 1011 or greater. In thefractionations with activated alumina, with Florisil, and with fullersearth, the n-pentane eluate was collected in two successive portions inorder to isolate fluorescence in the second portion. The results ofthese five fractionations in terms of quantities and characteristics ofthe fractions obtained are given in Table IX below for the bauxite andalumina fractionations and in Table X below for the fractionations withthe non-alumina absorbents.

TABLE IX Absorbent Activated Bauxite (Porocel, Activated Alumina (80-200mesh) 60-100 mesh) Eluant n-pentane benzene 25% ethanol n-pentanebenzene 25% ethanol in benzene in benzene Mass Recovery:

Wt. Percent of Charge 55.3 21.1 8.1 44.3 9.6 19.6 0.0

Total, Wt. Percent 84. 5 79. 5

Sulfur Content: Wt. Percent 0.03 4.35 4.82 0.02 0. 4.72 4. 56

Sulfur Recovery:

Wt. Percent of Sulfur in charge 1.12 65. 5 27. 9 0. 6 3. 4 60. 4 19. 8

Total Wt. Percent 94.6 90.2

Appearance colorless orange oil. black tar colorless colorless darlllrred black tar.

o1 o' 0' 0' Odor pleasant," unpleasant asphaltic pleasant..- pleasantunpleasant asphgltic phenolic. Fluorescence (Under ultraviolet light)trace of trace of greenbrown.

blue. blue. Corrected MassReoovery: 2 Wt. Percent 13 20 6.

of Charge.

2 All material losses were light ends.

TABLE X Adsorbent Florisil (30-170 mesh) Fuller's Earth (30-170 mesh)Silica Gel (28-200 mesh) 25% etha- 25% etha- 25% etha- Eluant n-pentanebenzene nol in n-pentane benzene n in n-pentane benzene 1101 in benzenebenzene benzene Mass Recovery:

Wt. Percent of Charge 12. 4 54. 7 12.0 7 1 15.2 46. 4 l0. 5 8. 6 58. 423. 3 1. 1

Total, Wt.

Percent 86.2 80. 7 82.8

Sulfur Content, Wt.

Percent 0. 33 1. 24 4. 61 3. 0.31 1. 29 5.05 3. 41 0. 74 3. 91 3. 4O

Sulfur Recovery:

Wt. Percent of S in Charge 2. 9 48. 8 39. 9 16.1 3. 4 43. 0 37. 9 21.031.0 65. 5 2. 6

Total, Wt.

Percent 107.7 105.3 99.1

Appearance colorless pale yel- Orangeblack tar colorless colorlessorange black tar brownbrownblack oil. low oil. red oil. oil. oil. oil.blf-ck bliick tar.

or o1 Odor pleasant unpleasunpleasasphaltic pleasant slightlyunpleasasphaltic pleasant unpleasphenolic.

ant. ant and and pheunpleasant. and pheant.

aisphalnolic. ant. nolic.

c. Fluorescence (under trace of blue yellow brown.-... trace of blueyellow.- brown....- mixed... mixed... mixed.

ultraviolet light). blue. blue. Corrected Mass Re- 75 24 1.1.

covery: 2 Wt. Percent of Charge.

1 Pentane eluate collected in two successive portions to isolate most offluorescence in latter portion.

1 All material losses were light ends.

that the lowest sulfur fraction obtained with the alumina V adsorbentcontained only 0.02 percent sulfur and amounted to 44.3 weight percentof the charge, or 61 weight percent of the charge based on correctedmass recovery.

The data in Tables IX and X show the complete difference in kind of ourprocess from processes employing non-alumina adsorbents. With thenon-alumina adsorbents it is impossible to obtain in any substantialyield a pentane eluate which is substantially sulfur-free as in ourprocess. As Table X shows, the pentane eluate of the silica gel processeluted a fraction having a sulfur content of 0.74 percent. In collectingthis fraction the poor colorretention properties of the silica geladsorbent were clear- 1y demonstrated. Even the first drop of the firstfraction emerging from the adsorbent was dark colored. There was nocolorless material at all. Table X shows that in the Florisil andfullers earth processes, lower sulfur contents than with the silica gelprocess were obtained by collecting the pentane eluate in two portions.Thus, the first portion of the pentane eluate in the Florisil processhad a sulfur content of 0.33 percent and in the fullers earth process asulfur content of 0.31 percent. However, the yields of these relativelylow sulfur fractions were very low, namely 12.4 percent of the charge(uncorrected) in the Florisil process and 15.2 percent of the charge(uncorrected) in the fullers earth process. These results compare veryunfavorably with the results of our process listed in Table IX.

In the foregoing examples, we have described the use of relatively highratios of eluant to charge. These ratios can be considerably lower thanused in the foregoing examples. As we have stated, the eluant to chargeratio in each elution stage is preferably from about 1 to 5 volumes ofeluant per volume of charge. Increasing the volume of eluant, or, inother words, the eluant to charge ratio, increases the liquid elutedfrom the column in each elution stage. However, a very high percentageof the material recoverable in an elution stage, e. g. 99 percent, canbe eluted by about 5 volumes of eluant per volume of charge so that theuse of a larger volume of eluant is generally not economicallyworthwhile. Example V below describes a fractionation in which we usedsomewhat lower charge to eluant ratios than in the previous examples.

Example V The McElroy crude of Table IH above was fractionated in acolumn of -200 mesh activated alumina using three successive eluants:n-pentane, benzene, and 25 volume percent ethanol in benzene. The chargeto adsorbent volume ratio was about 0.15 to l and about 35 percent ofthe adsorbent column was penetrated by the charge oil. In the firstelution stage n-pentane was introduced to the column in the amount of6.8 volumes per volume of charge. The n-pentane eluate was collected intwo portions in order to isolate fluorescence in the second portion. Theseparation of this cluate was at the point at which 5.7 volumes ofn-pentane per volume of charge had been introduced. Thereafter, 1.1volumes were used. The benzene was used in the amount of 5.0 volumes pervolume of charge and the ethanol-benzene eluant was used in the amountof 7.0 volumes per volume of charge. The results of this fractionationin terms of quantities and characteristics of the fraction obtained aregiven in Table XI below.

TABLE XI Eluant Recov- Total S Elemen- S Recov- Fluoresto charge cry,wt. Content, tal S Conery, wt. cencc under Crude Oil Fraction Eluantratio, percent wt. pertent, wt. percent Appearance Odor Ultra-vio- No.volJvol. of charge cent of percent of of sulfur let light fractionfraction in charge 1 (a). n-pentanc 5. 7 49. 6 0. 011 0. 00001 0.2colorless oil pleasant..." none. 1 (b) 1.1 19. 7 0. 53 0.011 4.4 do dopale blue.

McElroy Crude, 2.38% total 6. 8 69. 3

S, 0.506% elemental S.

2 benzene 5.0 20.0 6. 40 55. 4 brown o1l unpleasant blue-green. 3 vol.percent 7.0 10.0 7. 90 33.2 brown-black asphaltlc brown.

ethanol in bensemi-solid.

zone. Total Recovery" 99. 9 93. 2

Table XI shows that the n-pentane fraction obtained with the 6.8 to 1eluant to charge ratio amounted to 69.3 percent of the crude oilcharged. The table also shows that 99.9 percent of the crude oil wasrecovered in the three elution stages. There were no substantialmaterial losses in this fractionation.

The results in Table XI show very clearly another valuablecharacteristic of our process. This characteristic is in the productionof a fraction which is free of elemental sulfur. Elemental sulfur isknown to be the most undesirable form of sulfur present'in crude oilbecause of its highly corrosive nature. Therefore, the reduction of thevolumes per volume of charge. When 2.8 volumes of eluant per volume ofcharge had been introduced, the emerging eluate began to show light bluefluorescence in ultraviolet light, and the eluate emerging from thecolumn thereafter was collected separately. After this point, 1.4volumes of the first eluant per volume of charge were added. After thefirst stage elution, the adsorbent bed was eluted with benzene in theamount of 6.7 volumes per volume of charge and then with a mixture ofvolume percent ethanol in benzene in the amount of 51 volumes per Volumeof charge. The results of this fractionation are given in Table XII,below.

TABLE XII Eluant Recov- Sulfur Sulfur Fluoresto cry, Content, RecovceneeCrude Oil Fraction Eluant Charge Wt. Wt. cry, Wt. Appearance Odor underN0. Ratio, Percent Percent Percent U. V. vol./vol. o of S in LightCharge Fraction Charge 2,3 dimethyl butane. 2. 8 33.9 0.008 0.19Colorless oil... pleasant... none. 1.4 42.0 0.29 8. 52 do do pale blue.

4. 2 75. 9 West Texas Crude, 1.40% S... I

benzene 6. 7 22. 5 3. 86 60. 7 Brown 01l unpleasant bluegreen. 35 Vol.percent eth- 5.1 7. 54 3. 17. 92 Brown-black asphaltie brown.

anol in benzene. semi-solid;

Total Recovery 105. 9 87. 3

elemental sulfur content in motor fuel or cracking stock fractions iseven more important than the reduction of combined sulfur content. TableXI shows that in Example V the first portion of the n-pentane eluatewhich amounted to 49.6 percent of the crude, contained less than 0.00001weight percent elemental sulfur, as compared with the McElroy crude oilcharge which contained 0.506 weight percent elemental sulfur.

The results of Table XI are also of interest in con- Example VI The WestTexas crude of Table II was fractionated in a column of 80200 meshactivated alumina, using a charge to adsorbent ratio of 0.20 voiumc ofcharge per volume of adsorbent. This quantity of charge penetrated about40 percent of the adsorbent bed. Immediately after introduction of thecrude oil charge, the bed was eluted with 2,3-dimethyl butane in theamount of 4.2

Table XII shows that the same excellent results are obtained usingthe'branched chain paraffin, 2,3-dimethyl butane, as the first stageweak eluant, as are obtained with normal pentane. Thus, the two portionsof the weak eluant fraction amounted to about 75.9 weight percent of thecharge oil. This fraction was a colorless oil of pleasant odor, thefirst portion of which had a negligible sulfur content of only 0.008weight percent. Table XII also shows the excellent results obtained withrather low eluant to charge ratios. Excellent fractionation and highrecoverieswere obtained using only 4.2 parts of first stage eluant perpart of charge and 6.7 and 5.1 parts of eluant per part of charge in thesecond and third clution stages, respectively. It will be noted that thetotal recovery exceeds. lOO percent. The probable explanation is thateach eluate fraction contained a small amount of uncvaporated eluant.

It must also be understood that the colorless, low sulfur fractions.obtained with the first-stage eluants by our process are substantiallymetal-free and contain substantially all of the mononuclear aromaticcompounds of the original crude. The characteristic of our process ofproducing metal-free fractions is very important because if metalsarepresent in liquids subjected to catalytic treatments such. as cracking,such metals can have a seriously' adverseeffect on the; catalysts. Forthese reasons the substantially metal-free fractions of our process,when distilled, yield' ideal catalytic cracking stocks.

The metal contents of the fractions obtained in our process areillustrated by vanadium analyses on the fractions obtained infractionating the total West Texas crude oil of Table II above inaccordance with our process using three eluants, namely n-pentane,benzene, and

18 oil can be performed in such a manner. However, as we have mentioned,it is preferable in our process to take advantage of the diiferences inadsorbability of the various petroleum compounds which cause suchcompounds to 25 percent ethanol in benzene. The analyses were madeiislle successively from the 601112111 and to Collect the qon compositeeluate fractions from several different fraculd from the adsorbentcolumn 11 Several POI'UOIIS Which tionations of the mentioned West Texascrude. The cof'ltalll elthel a Single WP a YP ofcompoundsvanadiumcontents of these fractions are listed in Table Thls procedure ofcollqctmg h llould emerging t the XIII below. The West Texas crude oilbefore fractionaadsorbent Column durlng elutlofl 111 Several Portionstion contained 0.000380 percent by weight vanadium. be PP to y One allthe ellltlOIl Stages 0111' fractionation process. We have collected thefirst stage TABLE XIII eluate in a fractionation of the West Texas crudeof Table II through bauxite, in accordance with our process, in FractionRecovery Vanadium 2 533? twelve different portions. The procedureemployed is de- Wt. Per Content of Wt. Per- 16 scrlbed Exmple VIIbelowcent of Appearance Fraction, cent of No. Eluant o n t ie Wt.Percentvat ai m Example VII In I'll e Oil The West Texas crude was introducedto a column of 60-100 mesh activated bauxite (Regular Iron Porocel) 1--n-pentane. 75 ok les s oi l nfl 8. $821 in a charge to adsorbent ratioof 0.15 volume of crude oil 3:: g g gl f ag 0100738 97+ per volume ofadsorbent. About percent of the colinbenumn was penetrated by the 011.Immediately after introduction of the charge, the column was eluted withn-pentane in the amount of 6.0 volumes per volume of charge. Fr m Ta leXIII a v It can be Seen that the 9 25 The liquid emerging from thecolumn was collected in less first fraction which is eluted from thecolumn with twelve portions, the first eleven of which each containedll-pentane and Whlch cofltalns about 75 We1ght P t about 5.5 weightpercent of crude oil charged and the of the crude oil charged, wassubstantially v l twelfth of which contained 3.2 weight percent of thefree. The value for vanadium contentof th1s fraction crude. The resultsof this fractionation are given in which is listed in Table XIII is theminimum detectable Table XIV below.

TABLE XIV Rings per Molecule Aromatics, Moles per Liter 1 FluorescenceWt. Molecu- (Van Nes and Van (Lipkin and under Fraction N0. Percent larWeston Method) 2 Martin) 3 Ultra-violet of Crude Weight Light Mono- Di-Tri- Aromatic Naph- Aromatic nuclear nuclear nuclear thenic 5.5 320 o 0as 245 0 0.4 5.6 215 0 0.6 2:1 3%?) 3 8:2 5.5 255 0 0.5 5.7 230 0 0.65.5 240 0 0.6 5. 6 255 4 10- 10- 10- 0 0. 6 5. 3 260 5 10- 10- 10- 0 0.7 5.4 360 3 2 10- 4x10- 0.6 1.2 3.2 400 4 10- 1. 5X10 0.9 0.9

Total 64.2

1 Determined by ultraviolet light absorption spectroscopy. 2 K. Van N asand H. A. Van Weston, Aspects of the Constitution of Mineral Oils,Elsevier Publishing Co., Inc, New York,

5 M. R. Llpkin and C. C. Martin, Ind. Eng. Chem, Anal. Ed., vol. 19, p.183, 1947.

quantity of vanadium by the analytical method employed. However, it isprobable that the fraction was actually completely free of vanadium and,in any event, the vanadium content of this fraction was less than 1percent of the vanadium present in the original crude oil. The benzenefraction was also quite low in vanadium as the table shows, while thethird fraction which was eluted with the ethanol-benzene mixtureconstituted about 5 percent of the original crude and contained nearlyall of the vanadium present in the original crude. Table XIII shows thatconcentration of vanadium in the third fraction is about 19 times theconcentration of vanadium in the crude oil, so that in any process forthe recovery of vanadium from petroleum, this third fraction is aconsiderably better material for the process than the original crudeoil.

In each of the foregoing examples we have described recovering theeluate fractions in either one or, in the case of the pentane eluates,two portions. Such a procedure may often be desired and, as the examplesand tables show, an excellent primary fractionation of crude From theresults of Table XIV it can be seen that the first portion of thepentane eluate consisted entirely of paraffins, since no aromatic ornaphthenic rings were indicated. Fractions 2 through 8 inclusive weremixtures of parafi'ins and naphthenes as indicated by the presence ofnaphthenic rings and the absence of aromatic rings. The extremely lowaromatic content of the first 8 fractions is conclusively indicated bythe sensitive ultraviolet light absorption spectroscopy analysis.Fractions 11 and 12 contained high concentrations of mononucleararomatics. The dinuclear aromatic contents of these fractions were lowand the trinuclear aromatic contents were very low. From this table itcan be seen that the n-pentane eluate could be collected in threeportions to obtain a paraflinic portion, a portion consistingessentially of parafiins and naphthenes, and a highly aromatic portion.

In each of the foregoing examples, I though VII inclusive, thefractionations described were carried out at room temperature or fromabout 70 to F. and the liquids were passed through the adsorbent columnsby gravity flow. It should be understood, however, that other operatingconditions can be employed in our process. Thus, f r example, hoteluants can be used in certain of the on stages. Heating an eluantliquid increases its itivc power and, therefore, it is possible to usethe same ciuant liquid for two or more clution stages by introducing itto the adsorbent bed at successively higher temperatures for thesuccessive elution stages. It should be understood also that in ourprocess pressure can be applied to the liquid inlet end of the adsorbentbed or vacuum to the exit end if desired, to increase the rate of Howthrough the bed above the normal rate of gravity flow.

From the foregoing description of our invention it can be seen that wehave developed a process which can be of great value to the petroleumrefiner. Our process makes it possible to place the paraffinic,naphthenic and mononuclcar aromatic compounds of crude oil in fractionsof the crude separate from the sulfur and metal compounds. Thesulfur-containing components of the crude are segregated from thenon-sulfur components without subjecting them to elevated temperatures.In this Way the contamination of non-sulfur-containing fractions by thedecomposition of labile sulfur compounds during distillation is avoided,and also many valuable sulfur compounds can be recovered in theirnatural state for use as chemical agents or intermediates. Stillfurther, it is possible with out process to se :arate a crude petroleumoil into a large number of fractions diifering according to moleculartype by making appropriate cuts in each eluate emerging from theadsorbent bed.

Obviously many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof; therefore, only such limitations should be imposed as areindicated in the appended claims.

We claim:

1. A process for separating crude petroleum oil into low and 'highsulfur content fractions of unconverted, naturally-occurring petroleumcompounds which comprises passing into contact with a bed of adsorbentmaterial selected from the group consisting of activated alumina andactivated bauxite, a charge liquid comprising at least about 25 percentby volume of a sulfur-containing crude oil in an amount which penetratesno more than about 90 percent of the adsorbent bed, then contacting saidadsorbent bed with a wholly paraffinic eluant liquid in an amount atleast as great as the amount of charge liquid, recovering from the bedwith said paraffinic eluant liquid a parafiinic fraction of the crudeoil of low sulfur content, thereafter contacting said bed with at leastone additional eluant liquid, each eluant liquid having stronger elutingpower than the eluant used before it, and recovering from the bed withan eluant liquid of stronger eluting power than said paraffinic eluant afraction of said crude oil of high sulfur content.

2. The process according to claim 1 in which substantially all of theparaflinic, naphthenic and mononuclear aromatic compounds of the crudeoil are recovered in at least one fraction with said parafiinic eluantliquid and substantially all of the polynuclear aromatics and sulfurcomponents of the crude oil are recovered in at least one other fractionwith a stronger eluant.

3. A process for separating crude petroleum into low and highsulfur-content fractions of natural unconverted petroleum compoundswhich comprises passing into contact with a bed of activated alumina, aliquid comprising at least about 25 percent by volume crude oil in anamount which penetrates no more than about 90 percent of the aluminabed, then contacting said alumina bed with a wholly paraflinic eluantliquid, collecting eluate emerging from said bed until the eluate beginsto show fluorescence under ultraviolet light, separately collecting theremaining liquid eluted by said paraflinic liquid, thereafter contactingsaid bed with a series of eluants of successively increasing elutingpowers, and recovering separately each eluted fraction of unconvertednatural petroleum compounds.

References Cited in the file of this patent UNITED STATES PATENTS2,390,917 Brcth et al. Dec. 11, 1945 2,395,491 Mavity Feb. 26, 19462,441,572 Hirschler et al. May 18, 1948 2,509,486 Danforth May 30, 19502,571,936 Paterson et al, Oct. 16, 1951 2,574,434 Greentree et al. Nov.6, 1951 OTHER REFERENCES Pringsheim et al.: Luminescence of Liquids andSolids, Interscience Publishers, New York, N. Y. (1943), pages 72 and73.

Australian Chemical Institute, Journal and Proceedings, vol. 14, pages61-7 (1946). Abstracted in Chem. Abs, vol. 41, column 4913b (1947).

Cassidy: Adsorption and Chromatography, page 183 (1951), IntcrsciencePublishers Inc., 250 Fifth Avenue, New York 1, New York.

1. A PROCESS FOR SEPARATING CRUDE PETROLEUM OIL INTO LOW AND HIGH SULFURCONTENT FRACTIONS OF UNCONVERTED, NATURALLY-OCCURING PETROLEUMCOMPOJUNDS WHICH COMPRISES PASSING INTO CONTACT WITH A BED OF ASDORBENTMATERIAL SELECTED FROM THE GROUP CONSISTING OF ACTIVATED ALUMINA ANDACTIVATED BAUXITE, A CHARGE LIQUID COMPRISING AT LEAST ABOUT 25 PERCENTBY VOLUME OF A SULFUR-CONTAINING CRUDE OIL IN AN AMOUNT WHICH PERETRATESNO MORE THAN ABOUT 90 PERCENT OF THE ADSORBENT BED, THEN CONTACTING SAIDADSORBENT BED WITH A WHOLLY PARAFFINIC ELUANT LIQUID IN AN AMOUNT ATLEAST AS GREAT AS THE AMOUNT OF CHARGE LIQUID, RECOVERING FROM THE BEDWITH SAID PARAFFINIC ELUANT LIQUID A PARAFFINIC FRACTION OF THE CRUDEOIL OF LOW SULFUR CONTENT, THEREAFTER CONTACTING SAID BED WITH AT LEASTONE ADDITIONAL ELUANT LIQUID, EACH ELUANT LIQUID HAVING STRONGER ELUTINGPOWER THAN THE ELUANT USED BEFORE IT, AND RECOVERING FROM THE BED WITHAN ELUANT LIQUID OF STRONGER ELUTING POWER THAN SAID PARAFFINIC ELUANT AFRACTION OF SAID CRUDE OIL OF HIGH SULFUR CONTENT.